Ferguson plough

[Hair Bear]

Hi,
I've just acquired a Fergy plough that doesn't look 'normal'...
It's been stood 50 years to my knowledge and doesn't look like it's ever done a days work. All wearing parts look almost unused. The disc stems look standard but appear to have a 'shroud' welded over the disc arm pivot that restricts the disc swing (although it also has the usual chains), the rear wheel has a coil spring rather than a leaf spring, and the arm for the rear wheel is a casting rather than tubular. There doesn't appear to be any bodgery or modification to it, I would say it left the factory like it but I don't recall seeing anything like it before. Westlake appear to list the cast wheel arm and coil spring but don't give any clues to age/model etc. Can't find any reference to the shrouded disc stems at all. Could it be an early model? Could it be a 'Sherman'?
Any thoughts?